An elastic-wave reverse-time migration method based on optimal finite-difference operators using a new plane wave solution
ZOU Qiang1,2, HUANG Jianping1, YONG Peng1, LI Zhenchun1
1. School of Geosciences, China University of Petroleum(East China), Qingdao, Shandong 266580, China; 2. PetroChina Tarim Oilfield Company, Korla, Xinjiang 841000, China
Abstract：Elastic-wave revere time migration based on the theory of two-way wave equation is not limited by the dip angle of formation,so it has a strong adaptability to complex models.However,high computing cost and a large memory limit its application for processing big seismic data.This paper deduces an elastic-wave reverse-time migration imaging method using equivalent staggered-grid finite-difference based on time-space domain optimization.To improve imaging accuracy,we reduce the dispersion error by optimizing difference operators,which means that a low-order difference opera-tor can achieve the imaging accuracy of a high-order difference operator,so as to reduce the computing cost.To reduce memory usage, the second-order displacement equation is adopted to avoid intermediate variables.We also adopt an efficient boundary storage strategy，which uses the wavefield value near the boundary to control the reverse-time migration wavefield storage,which effectively reduces the memory use.Model tests show that the new method with a 6th-order spatial difference has a similar imaging accuracy to the conventional staggered-grid scheme with the 10th-order spatial difference,and the new method with a 10th-order corresponds to the conventional method with a 18th-order difference.Compared with conventional elastic wavefield storage strategy，effective boundary storage strategy can save a lot of memory usage on the premise of increasing less computing cost，and this strategy is more beneficial to shorter difference operators.
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ZOU Qiang, HUANG Jianping, YONG Peng, LI Zhenchun. An elastic-wave reverse-time migration method based on optimal finite-difference operators using a new plane wave solution. Oil Geophysical Prospecting, 2020, 55(5): 1047-1059.
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